JPH03148489A - Liquid storage tank - Google Patents

Abstract

PURPOSE:To obtain a liquid storage tank having no gap corrosion between a body and a reinforcing member, no crack of the body and sufficient pressure resistant strength by forming an interval of a reinforcing part small at the center of the body, large at the end, and a distance between the end of the body and the reinforcing part near the end longer than the distance between the reinforcing parts at the center of the body. CONSTITUTION:A liquid storage tank is formed of a cylindrical body 1, and upper and lower mirror plates 2, 3 of closing both ends of the body. A water supply port 4, and a hot water outlet 5 are respectively provided at the mirror plates, and a heating electric heater 6 is provided therein. A plurality of protrusions 8 are provided on the circumference of the body 1 in such a manner that the interval is narrow at the center of the body and larger toward the end. Accordingly, when negative pressure is generated in the tank, an action for deforming therein is operated at the body plate 1. In this case, since the rigidity of the plate is enhanced by the cylindrical protrusions 8 provided on the plate 1, it is scarcely deformed, and since the protrusions 8 at the center of the plate of weakest part is narrow at the interval,the rigidity of the body of this part is largest so that the deformation scarcely occurs.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a tank for storing liquid, and more specifically to a liquid storage tank suitable as a hot water storage type water heater.

[Conventional Technique III] Tanks configured to store liquid inside, especially tanks of push-up water heaters equipped with internal heaters,
For example, as disclosed in Japanese Utility Model Application Publication No. 62-76863, a reinforcing ring is welded inside the tank. That is, as shown in FIGS. 6 and 7,
The liquid storage tank is part 1.

It consists of an upper mirror plate 2 and a lower mirror plate 3 that close both ends of the body, and these are integrated by welding. Also 4
5 indicates a water supply port, and 5 indicates a hot water outlet, which are joined to the lower end plate 3 and the upper end plate 2, respectively. A heater 6 is connected to an external power source, and when energized, the cold water inside the tank is heated to hot water.

A reinforcing ring 7 having a cross-sectional shape shown in FIG. 7 is provided on the inner circumference of the body plate 1.
are fixed by welding.

Fill the tank 1 configured as above with water,
When the heater 6 is energized, the water becomes hot from the upper part of the tank. Therefore, for example, when tap water is supplied from the water supply port 4, the hot water is pushed up by the cold water, and the hot water is heated for 1 second from the tap water outlet 5.

By the way, if the pipe (not shown) connected to the hot water outlet 5 is connected to a position below the tank, and the water supply port 4 is blocked for some reason, the pipe connected to the hot water outlet 5 is At the same time as opening the hot water tap at the tip, a negative pressure equivalent to the head pressure corresponding to the head difference between the hot water tap and the tank is generated inside the tank.
Although the body plate l tends to deform inward, the reinforcing ring 7 prevents the deformation.

[Problem to be solved by the invention] As described above, the conventional technology prevents deformation of the tank, but
Since the reinforcing ring is fixed to the body by welding, crevice corrosion occurs between the reinforcing ring and the body, resulting in a shortened service life.

Furthermore, since a reinforcing ring is attached, there are also drawbacks such as increased cost. On the other hand, liquid storage tanks or hot water storage tanks are also known in which protrusions are integrally formed on the tank body plate in the circumferential direction instead of this reinforcing ring, but in order to increase the strength,
Since the protrusions are formed at equal intervals, narrow, and high, minute cracks may occur in the protrusions during the process of forming the protrusions.

Therefore, an object of the present invention is to provide a liquid storage tank that has sufficient pressure resistance strength without fear of crevice corrosion between the body and the reinforcing member, without fear of cracks in the body. It is said that

[Means for Solving the Problems] In order to achieve the above object, the present invention includes a plurality of reinforcing portions arranged in a ring shape in the circumferential direction on a body portion constituting a liquid storage tank. The spacing between these reinforcing parts is narrow at the center of the body and wide at both ends. Alternatively, the distance between the end of the barrel and the reinforcement close to this end is selected to be greater than the distance between the reinforcements in the center of the barrel.

The reinforcing portion may be formed by deforming the body portion into a protrusion or a concave shape.

[Function] Since the present invention has the above configuration, when fluid is stored,
It can sufficiently withstand both positive pressure and negative pressure. The reason for this is explained below. Generally, the following calculation formula is used to determine the internal negative pressure strength of a tank using a thin-walled cylinder. However, this applies when the copper plate or body is formed into a perfect circle, and in actual products where a flat plate is roll-formed and both ends are joined, deformation will begin at a value lower than the strength calculated using this calculation formula.

Also. If the reinforcing parts provided on the body plate have sufficient rigidity, the following formula can be used to calculate the pitch between the reinforcing parts. , the value of the following equation cannot be considered as the pitch of the circumferential protrusion.

P: Deformation pressure (kgf/cst") l: Axial length of shell plate (1) γ: Radius of copper plate (3) ν: Poisson's ratio of copper plate material E: Longitudinal elastic modulus of shell plate material (kgf/am") t: Thickness of copper plate (all) As is clear from the above formula, when the reinforcing portions are provided densely, the space becomes smaller and the pressure resistance is improved. However, if the spacing between the reinforcing parts is made smaller, the number of reinforcing parts increases, resulting in an increase in cost. Furthermore, if the reinforcing portion is constructed from a member separate from the body, not only will the cost increase, but the number of crevice corrosion locations will also increase. Furthermore, if the reinforcing part is formed integrally with the body, the risk of cracking the body will increase even further if a protrusion is formed on the ti.

By the way, in the present invention, since the number of reinforcing parts is reduced at both ends of the body, there are fewer problems such as those mentioned above.In other words, when considering the strength of the body,
Since mirror plates are integrally attached to both ends of the body by welding or the like, these mirror plates also act as reinforcing materials, and the strength of both ends is generally greater than that of the center. However.

Conventionally, reinforcing portions were provided uniformly over the entire body, which resulted in a large number of reinforcing portions, causing the above-mentioned problems.

As described above, according to the present invention, reinforcing portions are provided only at necessary positions, that is, a plurality of circumferential reinforcing portions are provided on the circumference of the torso, with many in the center in the axial direction of the torso, and more at the ends. The number of reinforcing parts is reduced, or the spacing between the end part and the reinforcing member near the end part is larger than the spacing in the center part, so that the above-mentioned conventional drawbacks are eliminated. ing. Furthermore, since the reinforcing portions are provided at necessary locations, the effect is the same as reducing the consideration in the calculation formula and increasing t, and the negative pressure strength of the tank is improved.

[Example] When carrying out the present invention, it is desirable to form the reinforcing portion by deforming the plate of the body portion into a rib shape, because it is easy to form and there is no problem of crevice corrosion. Also.

At this time, if the material of the body is rust-free steel, it is desirable to keep the height of the reinforcement part 1 or the rib to within 10% of the elongation rate that can be processed.If it exceeds this, there will be a problem of cracking due to processing. This is because it occurs. For these reasons, in the illustrated embodiment the reinforcements are shown in the form of ribs.

Hereinafter, one embodiment of the present invention will be described with reference to the drawings.

The liquid storage tank according to this embodiment consists of a cylindrical body 1 and upper and lower end plates 2.3 that close both ends of the body, and each end plate has a water supply port 4. It is the same as in the prior art that a tap 5 is provided and an electric heater 6 for heating is provided inside.

As shown in FIGS. 1 and 2, the body 1 is provided with a plurality of circumferential protrusions 8 on its circumference.

The circumferential protrusions or ribs 8 are narrowly spaced at the center of the copper plate or body, and are spaced more widely toward the ends.

Therefore, when negative pressure occurs inside the tank, the shell plate l
At this time, the rigidity of the body plate is increased by the circumferential protrusion 8 provided on the body plate l, so it is difficult to deform, and the center of the body plate, which is the weakest part, Since the intervals between the circumferential protrusions 8 are small, the rigidity of the copper plate in this part is the greatest, and deformation is less likely to occur.

Although the above example is an example in which a protrusion 8 protruding outward is formed on the plate constituting the body 1, the same effect can be achieved with a recess 8' that is deformed inward as shown in Fig. 3. is clear.

Further, as shown in FIGS. 4 and 5, two series of circumferential recesses 8'' or protrusions 8'' are formed, respectively.

It can also be implemented by forming protrusions in opposite directions between two series of depressions, and forming depressions in opposite directions between two series of protrusions 8. When carried out in this manner, the pressure resistance strength is further improved.

Although not shown in the drawings, a reinforcing ring is attached by welding or the like to the center of the body, which is most susceptible to pressure deformation, and other parts are formed by deforming the body to form protrusions or depressions. It is also possible to form a tank by deep-drawing the end plate without using the body plate, overlapping the two ends, and integrating them by welding.In this case, the welded part is located approximately at the center of the tank in the axial direction, and this welded portion improves the strength, making it possible to reduce the number of reinforcing portions. Also. The tank body may be formed by welding the ends of a large number of short cylinders together, and this overlapping welded portion may function as a reinforcing portion.[Effects of the Invention] As described above. Furthermore, according to the present invention, the spacing between the reinforcing parts provided in the body is narrow at the center of the body and wide at both ends, so the number of reinforcement parts can be reduced, so the problem of crevice corrosion is reduced. Moreover, there is no problem of cracking when the reinforcing portion is integrally formed.

Moreover, since reinforcement parts are provided at necessary positions, pressure resistance can be ensured without increasing the thickness of the body or reducing the volume, making it possible to obtain a low-cost, high-quality liquid storage tank. It will be done.

[Brief explanation of the drawing]

1 to 5 show an embodiment in which the present invention is applied to an electric water heater, FIG. 1 is a sectional view showing the whole, and FIGS.
Each figure is a sectional view of a main part showing different examples, FIG. 6 is a sectional view showing a conventional example, and FIG. 7 is a sectional view showing the main part. 1...Body part (copper plate) 2.3-・End plate 8.8,
8", 8"''' - Reinforcement part (protrusion or recess) Fig. 1 Fig. 4 Fig. 5111 Fig. 6 # 1 11, = Fig. 7 □1

Claims (1)

[Claims] 1. Consists of a cylindrical body and an end plate that is integrated to close both ends of the body, and a plurality of reinforcing parts are provided in the circumferential direction of the body. In the liquid storage tank, the spacing between the reinforcing portions is smaller at the center of the body and larger at the ends, or the distance between the end of the body and the reinforcing portion near the end is greater than the distance between the reinforcing portions. A liquid storage tank characterized in that the distance between the reinforced parts is greater than the distance between the reinforced parts in the central part of the parts. 2. The liquid storage tank according to claim 1, wherein the reinforcing portion is a projection or a recess formed integrally with the body. 3. The liquid storage tank according to claim 2, wherein the protrusions or depressions are formed in two rows in the axial direction, and the center portions thereof are formed as depressions or protrusions in opposite directions.